Drop loading-phase values if --discard_analysis_cache is true and we're not keeping incremental state.

PiperOrigin-RevId: 151639711
diff --git a/src/main/java/com/google/devtools/build/skyframe/InMemoryGraph.java b/src/main/java/com/google/devtools/build/skyframe/InMemoryGraph.java
index edb80f0..82ddb17 100644
--- a/src/main/java/com/google/devtools/build/skyframe/InMemoryGraph.java
+++ b/src/main/java/com/google/devtools/build/skyframe/InMemoryGraph.java
@@ -44,4 +44,6 @@
 
   // Only for use by MemoizingEvaluator#delete
   Map<SkyKey, ? extends NodeEntry> getAllValues();
+
+  Map<SkyKey, ? extends NodeEntry> getAllValuesMutable();
 }